Commissioning and initial operation experience with ASDEX Upgradeʹs new real-time control and data acquisition

ASDEX Upgrade was equipped with a distributed real-time (RT) control and diagnostic system. Application processes can be freely mapped onto controllers. They communicate through RT data exchanged via a shared memory network. Processes run self-organized with a data-driven scheme, i.e. a process executes when all required data has become available and produced data drive other processes waiting for these. The process chain starts periodically through a time-synchronous cycle master process to deterministically execute closed-loop control. Generic processes were implemented for feedback of plasma position and shape, and for performance control with fuelling and heating systems, for evaluation and monitoring of plasma quantities and Tokamak components, and generation of reference values in RT. Upon commissioning the system was speed-optimized to run a 1.6 ms cycle. Methods to exchange data and time information in RT and operate distributed data-driven processes work efficiently and reliably. The ability to freely map processes to computing nodes and RT data to generic processes provides outstanding configurational flexibility for optimizing system performance or supporting in situ replay and simulation runs. In the computation of reference values in RT acting on underlying feedback controllers, demonstrated for soft-landing, we see great potential to counteract instabilities or optimize pulses.